Subject: Re: [tbench regression fixes]: digging out smelly deadmen.
From: Mike Galbraith <efault@gmx.de>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jiri Kosina <jkosina@suse.cz>, David Miller <davem@davemloft.net>,
       rjw@sisk.pl, Ingo Molnar <mingo@elte.hu>, s0mbre@tservice.net.ru,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
       Andrew Morton <akpm@linux-foundation.org>
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Date: Sun, 26 Oct 2008 10:15:46 +0100
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On Sun, 2008-10-26 at 10:00 +0100, Peter Zijlstra wrote:
> On Sun, 2008-10-26 at 09:46 +0100, Mike Galbraith wrote: 

> > I reproduced this on my Q6600 box.  However, I also reproduced it with
> > 2.6.22.19.  What I think you're seeing is just dbench creating a
> > massive train wreck. 
> 
> wasn't dbench one of those non-benchmarks that thrives on randomness and
> unfairness?
> 
> Andrew said recently:
>   "dbench is pretty chaotic and it could be that a good change causes
> dbench to get worse.  That's happened plenty of times in the past."
> 
> So I'm not inclined to worry too much about dbench in any way shape or
> form.

Yeah, I was just curious.  The switch rate of dbench isn't high enough
for math to be an issue, so I wondered how the heck CFS could be such a
huge problem for this load.  Looks to me like all the math in the
_world_ couldn't hurt.. or help.

	-Mike

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